Pipe coating

ABSTRACT

Apparatus ( 1 ) for enabling a coating to be applied to an internal surface of a pipe elbow or bend C comprises a flexible body ( 2 ) adapted for location to extend within the pipe elbow or bend, and a bendable core ( 3 ) extending through the body. Bending of the core causes the flexible body to be bent in a similar manner. A method for applying the coating to the internal surface of the pipe elbow or bend (C) comprises the steps of shaping the flexible body ( 2 ) and locating it to extend within the pipe elbow or bend, and introducing a coating material so as to flow around and into a space defined between the flexible body and the internal surface of the elbow or bend.

TECHNICAL FIELD

Disclosed is an apparatus and method for internally coating a pipe inthe form of a bend or elbow. Such coated pipe bends/elbows findparticular though not exclusive application in the mining and chemicalindustries when transporting abrasive, erosive and corrosive slurries,concentrates, tailings and other flowable solid and/or liquid mixtures.The term “pipe” as employed herein is intended to include ducts,conduits, pipelines, tubes, chutes, cylinders and so on.

BACKGROUND ART

The mining industry employs ore and concentrate pipes to transport ores,concentrates, tailings and other materials over long distances. Suchpipes can be constructed from metal/metallic sections joined together toform an extended pipeline, and the ores being conveyed can often be inthe form of wet slurries or even dry particulate solids.

Many changes of direction can occur along the path of such pipelines,both in the vertical and in the horizontal plane, requiring the use ofelbows and bends. Some such elbows and bends can turn the pipeline up toangles of 180°, for example, in energy dissipation stations used withpipelines that fall from elevations exceeding 500 meters.

When transporting material such as abrasive/erosive/corrosive slurries,concentrates, tailings, a high level of pipe erosion can occur,especially at any bends in the pipeline, and most especially where thebends are located at the end of a pipeline fall. To avoid wear and/orcorrosion, the piping can be internally coated with an elastomericmaterial (e.g. rubber, or a synthetic material such as polyurethane orthe like).

Pipe diameters in such pipelines can vary between 50 and 500 mm, with itbeing desirable for each given pipe diameter to have a continuouscoating of elastomeric material throughout its length. In some instancesa specific uniform thickness is desirable and the coating thickness isselected specifically to the pipe diameter.

Coatings of rubber are most used for coarse particulate materials with asize above 2 mm due to the better resistance afforded by rubber at suchparticle sizes. For smaller particle size materials, polyurethane offersbetter resistance to abrasion. Thus, for materials such as concentratesand tailings, usually polyurethane is used as the coating material.

A uniform coating is more easily applied to straight sections of pipe,but less so in the bends and elbows, where it is difficult to achieve auniform thickness, especially when the coating to be applied is of asynthetic type, such as polyurethane.

SUMMARY OF THE DISCLOSURE

In a first aspect there is disclosed apparatus for enabling a coating tobe applied to an internal surface of a pipe elbow or bend. The apparatuscomprises:

a flexible body adapted for location to extend within the pipe elbow orbend; and

a bendable core, extending through the body, whereby bending of the corecauses the flexible body to be bent in a similar manner.

The apparatus can facilitate the application of an internal coating(lining) having a uniform thickness and can be used to apply coatings ofsynthetic elastomeric materials, such as polyurethane. In this regard,the radius of curvature of the body can be adapted (matched) to theinternal radius of curvature of the pipe elbow or bend. Using thebendable core, the flexible body can be shaped (e.g. by hand or by atemplate/tool in a preset way) so as to define a uniform annular spacebetween the elbow/bend internal wall and the body's external surface.This space is then able to be filled with a uniform coating oferosion-resistant, elastomeric material. Once the coating hascured/solidified, the flexibility of the body then facilitates an easyapparatus extraction.

In other arrangements, the internal coating need not be of uniformthickness. This can be achieved by defining different shapes of annularspace between the external surface of the flexible body and theelbow/bend internal wall.

Throughout this specification when the term “coating” is used it isinterpreted to mean both linings of any thickness of material, from asingle layer (such as one made of polyurethane) to a thick wearresistant liner (such as one made of rubber or harder materials such asceramic).

In one embodiment the flexible body is elongate and has a profile which,when the core is suitably bent, can approximate the profile but bespaced from the internal surface of the pipe elbow or bend. For example,the flexible body may have a cylindrical profile and may be formed froman elastomeric material. The core can then extend centrally through thecylindrical body.

The flexible body can be of polyurethane. The core can be formed from abendable metallic rod. In one embodiment the core can have a rectangularcross-sectional profile. In this embodiment the height of the coreprofile may range between 0.3 D and 0.7 D, and the thickness of the coreprofile may range between 0.01 D and 0.06 D, where D is the internaldiameter of the pipe elbow or bend.

In one embodiment the body and core may be adapted at opposing endsthereof for being mounted to respective opposing ends of the elbow orbend. In one variation, the adaptation at each end of the body and corecan comprise a disk that extends across a respective end of the body.The disk can be connected to the core, centrally at a disk face.

In one embodiment the adaptation at each end of the body may furthercomprise a body flange that is adapted for being coupled to respectivepipe coupling flanges located at respective ends of the pipe elbow orbend. Each body flange may be releasably coupled to a respective end ofthe body via the disk and through the use of one or more releasablefasteners. Each body flange may be of metal and can be adapted for beingbolted to its respective pipe coupling flange. Each body flange may alsocomprise a pathway through which a flowable coating material can beintroduced when the apparatus is located in the pipe elbow or bend.

In one embodiment the apparatus can further comprise:

(i) a mechanism for adjusting the body length with respect to the elbowor bend; and/or(ii) a mechanism for adjusting the body orientation with respect to theelbow or bend.

The mechanism can comprise:

in (i) one or more washers for positioning adjacent to one or bothdisks;

in (ii) one or more wedges for positioning near to one or both disks.

In one embodiment the thickness of each washer may range between 0.5 and2 mm. The thickness of each wedge may, at its shorter side, rangebetween 0.5 and 2 mm. Further, the thickness of each wedge may, at itslonger side, range between 1 and 4 mm.

In one embodiment the diameter of the body can be selected such that inuse it leaves a space therearound that ranges between 3 and 25 mm withrespect to the internal wall of the elbow or bend. In still furtherembodiments the space between an outer surface of the flexible body andan inner surface of the pipe elbow or bend need not be evenly annular,in situations where the internal coating needs to be designed thicker insome places and thinner in others.

In one form the apparatus can take the form of a mandrel.

In a second aspect there is disclosed a method for applying a coating toan internal surface of a pipe elbow or bend, the method comprising thesteps of:

shaping a flexible body and locating it to extend within the pipe elbowor bend; and

introducing a coating material so as to flow around and into a spacedefined between the flexible body and the internal surface of the pipeelbow or bend.

The method can comprise the further steps of:

allowing the coating material to cure and/or solidify;

removing the flexible body so as to leave the coating material behind asa lining on the internal surface of the pipe elbow or bend.

The flexible body employed in the method of the second aspect can form apart of the apparatus of the first aspect, whereby the method can makeuse of that apparatus.

In the method the flexible body can be adapted to have a body flangeassociated with each end thereof. Thus, after locating the body toextend within the pipe elbow or bend, each body flange can be releasablycoupled to a respective end of the body using one or more releasablefasteners.

Further, after each body flange is releasably coupled to its respectivebody end, the body flange can be coupled to a respective pipe couplingflange located at an end of the elbow or bend using one or morereleasable fasteners.

In one embodiment of the method, each body flange can comprise a pathwaytherethrough, wherein the coating material can be introduced into thespace via at least one such pathway.

In one embodiment of the method, the body length and/or the bodyorientation may be adjusted with respect to the pipe elbow or bend. Inone embodiment of the method the step of adjustment of the bodyorientation occurs prior to introducing the coating material, so thatthe space is adjusted to a predetermined form. In other embodiments theadjustment of the body orientation can be made after the introduction ofthe coating material but prior to the solidification or curing of thecoating material.

DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms that may fall within the scope of theapparatus and method as set forth in the Summary, a specific embodimentof the apparatus and method will now be described, by way of exampleonly, and with reference to the accompanying drawings in which:

FIG. 1 shows a cross-section of a 90° elbow for use in a pipeline.

FIG. 2 shows an embodiment of an apparatus for enabling the internalcoating of the 90° elbow of FIG. 1.

FIG. 3 shows a cross-section of the apparatus taken on the plane A-A ofFIG. 2.

FIG. 4 shows a plan view of a position-adjusting washer and wedge foruse with the apparatus of FIG. 2.

FIG. 5 shows a side view of the position-adjusting washer of FIG. 4.

FIG. 6 shows a cross-sectional side view of the adjusting wedge of FIG.4.

FIG. 7 shows a combination cross-section of the 90° elbow shown in FIG.1 when fitted with the apparatus for enabling the internal coating ofthe 90° elbow shown in FIG. 2.

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENT

FIG. 1 shows a pipe elbow C in cross-section, comprising opposing unionflanges F for connecting to opposing sections of pipe. The bend in thepipe elbow has external and internal curvature radii, R_(e) and R_(i)respectively and an effective diameter D.

Referring to FIG. 2, an apparatus for enabling the internal coating ofthe 90° elbow of FIG. 1 comprises a mandrel 1 that is formed by acylindrical body of elastomeric material 2 (such as polyurethane). Aflexible core 3 extends through the centre of the cylindrical body 2, asdepicted in FIGS. 2 and 3. The core can be of a bendable metallic rod,and can be bent into shape to simulate the internal curvature (centralradius) of the elbow or bend.

Disks 4 are arranged at respective ends of the mandrel, with each disk 4being connected to the core 3 by a fastening mechanism. In theembodiment depicted the connection is effected by means of webstiffeners 5, which can be welded or bolted to the core 3 and to each ofthe disks 4.

To apply the coating internally to an elbow or bend the mandrel 1 is, inthis embodiment, fastened to and within the elbow C. In this regard,after appropriately shaping (e.g. by hand, or using a tool or template)and then locating the cylindrical body 2 within the elbow or bend,opposing flanges 6 are each bolted to a respective disk 4 by bolts 7. Inthe embodiment depicted, four bolts 7 are employed at each mandrel end.Each flange 6 is then bolted to a respective flange F of the elbow C bybolts (not shown). Each flange 6 is provided with a passage for feedingliquid polyurethane into the elbow or bend C, so as to flow around andsurround the cylindrical body 2, and to subsequently cure/solidify inthe annular space 20 which is shown in FIG. 3.

The diameter of the mandrel is selected such that it leaves an annularspace therearound that ranges from about 3 to 25 mm from the mandrel'soutside surface to the adjacent internal wall of the elbow C.

In the embodiment shown, the core 3 has a rectangular profile, wherein aheight h of the core 3 can be selected to range between 0.3 D and 0.7 D,and wherein its thickness can be selected to range between 0.01 D and0.06 D, where D is the internal diameter of the pipe.

In many cases, elbows or bends that are manufactured using non-fullyautomated methods can present minute differences and poorer tolerancesboth in their overall dimensions and in curvature of radii. Toaccommodate this, the length and curvature radius of the mandrel canreadily be adjusted to each particular elbow. In this regard, themandrel 1 is provided with washers 8 that allow the length of mandrel 1to be adjusted to suit the particular elbow. The washers 8 may have athickness ranging between 0.5 and 2 mm. Further, the mandrel 1 can beprovided with wedges 9 that can be used to regulate and adjust tovariations in the curvature radius in the manner of a cam adjustment.The wedges 9 may have a thickness ranging, at the shorter side, between0.5 and 2 mm and, at the longer side, between 1 and 4 mm. In order tomodify the position of the washers and wedges in relation to the bolts 7the washers 8 and wedges 9 are provided with grooves 10 (FIG. 4). Thisallows for washer rotation on an axis of core 3, to effect theadjustments to optimise the mandrel shape to the elbow interior profile.

In its method of use, a liquid polyurethane/rubber/ceramic liningmaterial is fed into the annular space which surrounds the mandrel 1 andis then allowed to cool and solidify over a period of time. In someembodiments it may be possible to make some adjustment to the positionof the mandrel 1 at this stage whilst the lining material is stillfluid, but normally the mandrel 1 position has been pre-determinedwithin the pipe bend or elbow C before the lining material is fed intothe annular space 20. After solidification the mandrel 1 is releasedfrom its coupled position to the pipe bend or elbow C by undoing theaforementioned flange bolts 7. The mandrel 1 is then slidinglywithdrawn, thereby leaving a corresponding elongate hole in the interiorof the lined pipe bend or elbow C.

In an embodiment, the elastomeric material of mandrel body 2 is formedof polyurethane, which can be adapted (e.g. spray-coated with a releaseagent) to facilitate its disengagement from thepolyurethane/rubber/ceramic lining material after the feeding in andcuring of that lining material in the elbow or pipe bend. The flexiblecore 3 can comprise a repeatedly bendable metal. The disks 4 and flanges6 are also of metal.

Whilst specific apparatus and method embodiments have been described, itshould be appreciated that the apparatus and method may be embodied inmany other forms.

In the claims which follow, and in the preceding description, exceptwhere the context requires otherwise due to express language ornecessary implication, the word “comprise” and variations such as“comprises” or “comprising” are used in an inclusive sense, i.e. tospecify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments of theapparatus and method.

1. Apparatus for enabling a coating to be applied to an internal surfaceof a pipe elbow or bend, the apparatus comprising: a flexible bodyadapted for location to extend within the pipe elbow or bend; and abendable core, extending through the body, whereby bending of the corecauses the flexible body to be bent in a similar manner.
 2. Apparatusaccording to claim 2, wherein the flexible body is elongate and has aprofile which, when the core is suitably bent, can approximate theprofile but be spaced from the internal surface of the pipe elbow orbend.
 3. Apparatus according to claim 1, wherein the flexible body iscylindrical and is formed from an elastomeric material, and wherein thecore extends centrally through the cylindrical body.
 4. Apparatusaccording to claim 3, wherein the body is of polyurethane.
 5. Apparatusaccording to claim 1, wherein the core is formed from a bendablemetallic rod.
 6. Apparatus according to claim 1, wherein the core has arectangular profile, with the height of the core profile ranging between0.3 D and 0.7 D, and with the thickness of the core profile rangingbetween 0.01 D and 0.06 D, where D is the internal diameter of the pipeelbow or bend.
 7. Apparatus according to claim 1, wherein the body andcore are adapted at opposing ends thereof for being mounted torespective opposing ends of the pipe elbow or bend.
 8. Apparatusaccording to claim 7, wherein the adaptation at each end of the body andcore comprises a disk that extends across a respective end of the body,with the disk being connected to the core, centrally at a disk face. 9.Apparatus according to claim 8, wherein the adaptation at each end ofthe body further comprises a body flange that is adapted for beingcoupled to respective pipe coupling flanges located at respective endsof the pipe elbow or bend.
 10. Apparatus according to claim 9, whereineach body flange is releasably coupled to a respective end of the bodyvia the disk and through the use of one or more releasable fasteners.11. Apparatus according to claim 10, wherein each body flange is ofmetal and is adapted for being bolted to its respective pipe couplingflange.
 12. Apparatus according to claim 9, wherein each body flangecomprises a pathway through which a flowable coating material can beintroduced when the apparatus is located in the pipe elbow or bend. 13.Apparatus according to claim 8, further comprising (i) a mechanism foradjusting the body length with respect to the elbow or bend; andier (ii)a mechanism for adjusting the body orientation with respect to the elbowor bend.
 14. Apparatus according to claim 13, wherein the mechanismcomprises: in said mechanism for adjusting the body length with respectto the elbow or bend one or more washers for positioning adjacent to oneor both disks; and in said mechanism for adjusting the body orientationwith respect to the elbow or bend one or more wedges for positioningnear to one or both disks.
 15. Apparatus according to claim 14, whereinthe thickness of each washer ranges between 0.5 and 2 mm, and whereinthe thickness of each wedge, at its shorter side, ranges between 0.5 and2 mm and, at its longer side, ranges between 1 and 4 mm.
 16. Apparatusaccording to claim 1, wherein the diameter of the body in use isselected such that it leaves a space therearound that ranges between 3and 25 mm with respect to the internal wall of the pipe elbow or bend.17. Apparatus according to claim 1, that is in the form of a mandrel.18. A method for applying a coating to an internal surface of a pipeelbow or bend, the method comprising the steps of: shaping a flexiblebody prior to locating it within the pipe elbow or bend; locating it theflexible body to extend within the pipe elbow or bend; and introducing acoating material so as to flow around and into a space defined betweenthe flexible body and the internal surface of the pipe elbow or bend.19. A method according to claim 18, comprising the further steps of:allowing the coating material to cure and/or solidify; and removing theflexible body so as to leave the coating material behind as a lining onthe internal surface of the pipe elbow or bend.
 20. A method accordingto claim 18, wherein the flexible body forms part of an apparatusaccording to claim
 1. 21. A method according to claim 20, wherein theflexible body is adapted to have a body flange associated with each endthereof, and wherein, after locating the body to extend within the pipeelbow or bend, each body flange is releasably coupled to a respectiveend of the body using one or more releasable fasteners.
 22. A methodaccording to claim 21, wherein after each body flange is releasablycoupled to its respective body end, the body flange is coupled to arespective pipe coupling flange located at an end of the elbow or bendusing one or more releasable fasteners.
 23. A method according to claim21, wherein each body flange comprises a pathway therethrough, whereinthe coating material is introduced into the space via at least one suchpathway.
 24. A method according to claim 18, wherein the body lengthand/or the body orientation is adjusted with respect to the pipe elbowor bend.
 25. A method according to claim 24, wherein the step ofadjustment of the body orientation occurs prior to introducing thecoating material.
 26. Apparatus according to claim 8, further comprisinga mechanism for adjusting the body length with respect to the elbow orbend.
 27. Apparatus according to claim 8, further comprising a mechanismfor adjusting the body orientation with respect to the elbow or bend.